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J Chromatogr B
Analyt Technol Biomed Life Sci. 2006 Nov 7;843(2):252-61.
Determination of zearalenone and its metabolites in urine, plasma and faeces
of horses by HPLC-APCI-MS.
Songsermsakul P, Sontag G, Cichna-Markl M, Zentek J,
Razzazi-Fazeli E.
The paper describes a method for the sensitive and selective determination of
zearalenone and its metabolites in urine, plasma and faeces of horses by high
performance liquid chromatography and atmospheric pressure chemical ionisation
(APCI) mass spectrometry (MS). While only one step sample clean-up by an
immunoaffinity column (IAC) was sufficient for plasma samples, urine and faeces
samples had to be prepared by a combination of a solid-phase extraction (SPE)
and an immunoaffinity column. The method allows the simultaneous determination
of zearalenone and all of its metabolites; alpha-zearalenol, beta-zearalenol,
alpha-zearalanol, beta-zearalanol and zearalanone. Dideuterated zearalanone was
used as internal standard for quantification and the study of the matrix effect.
Recovery rates between 56 and slightly above 100% were achieved in urine
samples, and more than 80% in plasma and faeces samples. The limits of detection
ranged from 0.1-0.5 microg/l or microg/kg, the limits of quantification from
0.5-1.0 microg/l or microg/kg. The practical use of the method is demonstrated
by the analysis of spiked and naturally contaminated urine, plasma and faeces of
horses.
PMID: 16828347
Toxicol Sci. 2006 Jun;91(2):448-55. Epub 2006 Mar 17.
The mycoestrogen zearalenone induces CYP3A through activation of the pregnane X
receptor.
Ding X, Lichti K, Staudinger JL.
Department of Pharmacology and Toxicology, University of Kansas, Lawrence,
Kansas 66045, USA.
Zearalenone is a mycoestrogen that is produced in the fungi Fusarium
graminearum, Fusarium culmorum, Fusarium equiseti, and Fusarium crookwellense.
These fungi commonly exist in agricultural products. Human pregnane X receptor
(hPXR) is a ligand-activated transcription factor that regulates the expression
of numerous hepatic drug-metabolizing enzymes, including several clinically
important cytochrome P450s. In this report, we show that zearalenone is an
efficacious ligand for hPXR. We also describe the creation and validation of a
novel adenoviral-mediated transduction protocol used to express functional
FLAG-tagged-hPXR protein in a transformed cell line (HepG2) and primary cell
types (cultured hepatocytes). Treatment of hPXR-transduced HepG2 cells with
zearalenone induces expression of CYP3A4, the "prototypical" PXR-target gene in
human liver. Treatment of hPXR-transduced cultured hepatocytes isolated from
PXR-knockout mice with zearalenone induces the expression of Cyp3a11, the
prototypical murine hepatic PXR-target gene. Using mammalian two-hybrid assays,
we show that zearalenone displaces the nuclear receptor corepressor protein
N-CoR from hPXR, while it recruits coactivator proteins steroid receptor
coactivator-1, Glucocorticoid Receptor-Interacting Protein 1 and PPAR-Binding
protein (GRIP1) and PBP to hPXR. Concentration-response analysis using a
PXR-responsive reporter gene assay reveals that zearalenone activates hPXR with
an EC50 value of approximately 1.5 microM. Because activation of hPXR represents
the molecular basis of an important class of drug interactions, our findings
suggest that studies to investigate the potential of zearalenone to induce the
metabolism of other drugs in humans are warranted. In addition, due to the
limited availability of primary human hepatocytes, our adenoviral-mediated hPXR
expression protocol will likely prove useful in studies of the xenobiotic
response.
PMID: 16547076 |
